Co-transmitting neurons in the lateral septal nucleus exhibit features of neurotransmitter switching.

The lateral septal nucleus (LSN) is a highly interconnected region of the central brain whose activity regulates widespread circuitry. As such, the mechanisms that govern neuronal activity within the LSN have far-reaching implications on numerous brain-wide nuclei, circuits, and behaviors. We found that GABAergic neurons within the LSN express markers that mediate the release of acetylcholine (ACh). Moreover, we show that these vGAT neurons release both GABA and ACh onto local glutamatergic LSN neurons. Using both short-term and long-term neuronal labeling techniques we observed expression of the cholinergic neuron marker Choline Acetyltransferase (ChAT) in vGAT neurons. These findings provide evidence of cholinergic neurotransmission from vGAT neurons, and provide an impetus to examine dynamic co-neurotransmission changes as a potential mechanism that contributes to neuronal and circuit-wide plasticity within the LSN.